1. Field of the Invention
The present invention relates generally to phosphor which is short in decay time and is directed more particularly to special phosphor (ZnCd)S:Ce, M which is of high peak intensity of light emission and suitable for use as a phosphor screen of a flying spot scanner tube or phosphor of a beam indexing color cathode ray tube for deriving an index signal and so on, and also to method of making the phosphor.
2. Description of the Prior Art
In the phosphor used as the phosphor screen of a flying spot scanner tube or the phosphor of a beam indexing color cathode ray tube for deriving an index signal, it is especially required that the attenuating time i.e. decay time of its light emission is as short as possible. Further, in order to improve the S/N ratio of a signal processing circuit therefor, it is desired that the intensity of light emission of phosphor is as high as possible so as to derive a large output from a detecting element such as a photo-diode.
In the art, as a phosphor which emits, for example, ultraviolet rays, Ca.sub.2 Mg Si.sub.2 O.sub.7 :Ce (P 16 phosphor) or Y.sub.2 Si.sub.2 O.sub.7 :Ce is used; as a phosphor which emits blue light, Y.sub.2 SiO.sub.5 :Ce or ZnO:Zn is used; and as a phosphor which emits green light, Y.sub.3 Al.sub.5 O.sub.12 :Ce (P 46 phosphor) or GdAlGaO.sub.4 :Ce is used, respectively.
Among these phosphors, the P 46 phosphor is greatest in intensity of light emission, but in view of improving the S/N ratio and so on, a phosphor, which is higher than the P 46 phosphor in intensity of light emission and shorter in decay time, is desired.